carapacial scute variation in green turtle (chelonia mydas and...

S. ERGENE, C. AYMAK, A. H. UÇAR

343

Turk J Zool

2011; 35(3) 343-356

© TÜBİTAK

doi:10.3906/zoo-0808-8

Carapacial scute variation in green turtle (Chelonia mydas)

and loggerhead turtle (Caretta caretta)

hatchlings in Alata, Mersin, Turkey

Serap ERGENE1,

*, Cemil AYMAK2, Aşkın Hasan UÇAR

3

1Mersin University Sea Turtles Application and Research Center, Mersin - TURKEY

2Kasım Ekenler Highschool, Çamlıyayla, Mersin - TURKEY

3Osmaniye Korkut Ata University, Faculty of Science and Arts, Department of Biology, 80010, Osmaniye - TURKEY

Received: 14.08.2008

Abstract: In recent years, Alata beach has been considered to be among 20 important sea turtle nesting areas in Turkey.

In the 2003 nesting season, the carapacial scute variation of 1086 Chelonia mydas hatchlings (169 dead and 917 live)

and 394 Caretta caretta hatchlings (74 dead and 320 live) from Alata beach in Mersin, Turkey, were examined within

carapacial scute series and in carapacial scute pattern.

Th e most frequent scute pattern observed for Ch. mydas hatchlings was 1 nuchal, 5 vertebrals, 1 pair of supracaudals, 4

pairs of costals, and 11 pairs of marginals. Th e pattern of 1 nuchal, 5 vertebrals, 1 pair of supracaudals, 5 pairs of costals,

and 12 pairs of marginals was the most frequent pattern for loggerhead hatchlings. Using the Minitab 13.0 Z test for 2

proportions, the numbers of variations on the carapacial scutes of dead and live hatchlings of Ch. mydas and C. caretta

were examined to see whether there was a relation between the rate of dead hatchlings and the number of variations on

the carapacial scute. It was found that there was no relation between the changes in variation numbers and the mortality

rates in Ch. mydas and C. caretta hatchlings.

Key words: Carapace, scute variation, Chelonia mydas, Caretta caretta, Alata

Alata, Mersin – Türkiye’deki yeşil deniz kaplumbağası (Chelonia mydas) ve iribaş

kaplumbağa (Caretta caretta) yavrularının karapas kabuğundaki farklılaşmalar

Özet: Son yıllarda, Alata kumsalı Türkiye’deki 20 önemli deniz kaplumbağası yuvalama alanlarından biri olarak

değerlendirilmektedir. Mersin’deki Alata kumsalında, 2003 üreme sezonunda, 1086 Chelonia mydas, (169 ölü ve 917

canlı) ve 394 Caretta caretta, (74 ölü ve 320 canlı) yavrularının karapas kabuğundaki farklılaşma karapas plak serileri ve

plak sıralanması bakımından incelenmiştir.

Ch. mydas yavrularında en çok gözlemlenen kabuk serisi 1 nukal, 5 vertebral, 1 çift suprakaudal, 4 çift kostal ve 11 çift

marginal şeklindedir. İribaş kaplumbağa için en çok tekrar eden kabuk serisi ise 1 nukal, 5 vertebral, 1 çift suprakaudal,

5 çift kostal ve 12 çift marginal şeklindedir. Minitab 13.0 ikili oran için Z testi kullanılarak, Ch. mydas ve C. caretta ölü ve

canlı yavrularının karapas kabuklarındaki farklılaşma, ölü yavruların oranı ile karapas kabuğundaki plak farklılaşması

arasında bir ilişki olup olmadığını görmek için incelenmiştir. Ch. mydas ve C. caretta yavrularında varyasyon sayısındaki

değişiklikler ve ölüm oranları arasında herhangi bir ilişki bulunamamıştır.

Research Article

* E-mail: [email protected]

Carapacial scute variation in green turtle (Chelonia mydas) and loggerhead turtle (Caretta caretta) hatchlings in Alata, Mersin, Turkey

344

Introduction

Two sea turtle species, Caretta caretta and

Chelonia mydas, nest regularly on the Turkish coast

of the Mediterranean (Geldiay et al., 1982; Baran

and Kasparek, 1989; Türkozan et al., 2003; Canbolat,

2004). Leatherback turtles (Dermochelys coriacea)

have also been reported on the Turkish coast (Oruç

et al., 1997; Baran et al., 1998; Taşkavak et al., 1998;

Sönmez et al., 2008). In Turkey, 20 important nesting

beaches for sea turtles were determined in various

studies (Baran and Kasparek, 1989; Baran, 1990;

Baran et al., 1992; T.Ç.O.B., 2005; Aymak et al., 2005;

Ergene et al., 2006a, Ergene et al., 2006b) (Figure 1).

Many scientists state that although the

arrangement and the number of scutes in turtles

are stable individual diff erences can be observed in

many turtle species (Gadow, 1899; Newman, 1906;

Hewavisenthi and Kotagama, 1989; Mast and Carr,

1989). Deraniyagala (1939) states that vertebral

scutes form carapace scutellation of a turtle. Vertebral

scutes are a series of unpaired pieces in the median

line, costal scutes are a bilateral series of paired scutes

on each side of the vertebral scutes, and marginal

scutes are a bilateral series of paired scutes encircling

the outer side of costal scutes. Th ere is a pair of

supracaudal scutes between the last pair of marginal

scutes. A nuchal scute is located anteriorly between

the fi rst pair of marginals (Figure 2).

In his study on C. caretta, Gadow (1899) concludes

that the proportion of variation in adults is less than

that of hatchlings. Starting from this fact, Gadow

(1899) puts forward the idea of orthogenetic variation.

According to this idea, in young turtles having diff erent combinations than normal components, scutes undergo fusion during ontogeny so that the adult stage shows the normal reduced scute pattern. On the other hand, Newman (1906) argues that supernumerary scutes are the atavistic reappearance of scutes lost during phylogeny (Türkozan et al., 2001). Özdemir and Türkozan (2006) explain the absence of adults with deviant numbers of costal, vertebral, nuchal, or supracaudal scutes in 2 ways: the hatchlings with deviant scutes die before they mature, or the scutes change to the normal number with growth. According to Zangerl and Johnson (1957), carapaces of turtles, while forming, remain stable during chelonian evolution.

Parker (1901), Hildebrend (1930), and Zangerl (1969) claim that this abnormal situation occurs accidentally or because of a disorder during ontogenetic development. Hildebrend (1938) says that the abnormal scutes of Diamondback terrapins are formed as a result of fl uctuations in oxygen levels during incubation. In addition, Kazmaier and Robel (2001) report that the greater number of scute anomalies in Terrapene ornata in central Kansas may be the result of variations in temperature or moisture that cause stress during egg development or incubation, or the mutagenic eff ects of excess salinity during those periods. Deviations from the normal scute formulae of turtles may also result from embryonic mutations, specifi c causes of which are unknown (Kazmaier and Robel, 2001).

Yntema (1976) and Yntema and Mrosovsky (1980) indicate that, regarding temperature-

Denizli

Muğla

EkincikDalyan

DalamanFethiye

PataraDemre(Kale)

Kumluca

Çıralı

BelekKızılot

Antalya

TekirovaDemirtaş

Gazipaşa

Mediterranean Sea

N36

38

Anamur

GöksuDeltas

ALATA

Mersin

Adana

KazanlıAkyatan

YumurtalıkSamandağı

Mediterranean Sea

TURKEY

T U R K E Y

36333027

50 0 50 100 150 km

Figure 1. Th e location of Alata in Turkey.


345

dependent sex determination, morphogenetic eff ects

can be observed in turtles as a result of changes in

temperature during incubation. As Mast and Carr

(1989) state, among sea turtles, Lepidochelys has the

highest rate of deviation in scutes. Furthermore,

handling the eggs during the development phase

increases scute variation in Lepidochelys olivacea

(Hill, 1971) and causes the mortality rate of embryos

to rise (Limpus et al., 1979). Th e above-mentioned

evidence demonstrates the eff ects of diff erent kinds

of environmental factors on scute variation during

incubation.

Th e main aims of this study were to provide

information about carapacial scute variation of

C. caretta and Ch. mydas hatchlings and to detect

whether there is a relationship between variation in

scute numbers and the mortality rate of hatchlings

of 2 species.

Materials and methods

Alata beach is located inside the borders of Alata

Horticultural Research Institute, which is one of the

1st degree natural sites. It is 3 km east of Erdemli and

30 km west of Mersin, and the nesting area is a 3-km-

long beach in front of the institute.

Th roughout the study, the whole beach was

monitored both night and day. During the night

studies, the sea turtles coming out of the sea to the

beach to nest were observed without interference.

Eight live female Ch. mydas that were found laying

eggs on the beach in 2003 and 5 Ch. mydas (sex

unknown) that were found dead on the beach (3 in

2002 and 2 in 2003) were measured and the scutes

of 13 adult individuals in total were counted. Th e 5

stranded dead individuals were so badly decomposed

that it was not possible to determine their sex. When

the variation numbers on the carapacial scutes of

the adult Ch. mydas were evaluated, the sex of the

adults and their being dead or alive were not taken

into consideration. Only an assessment of the general

situation of the 13 adults in total was made.

Emergences from the natural nests were recorded

during the hatchling season. Furthermore, 5-10 days

aft er the fi rst emergence of hatchlings, openings were

made in the nests to gather nest and egg data, count

dead embryos, and check the number of hatchlings.

In this study, all of the hatchlings found were grouped

N NM1M1

M12

C1

C2

C3

C

S S

4

C5

V5

V4

V3

V2

V1

M11

C1

C2

C

S S

3

C4

V5

V4

V3

V2

V1

Figure 2. Carapace in sea turtles A: Caretta caretta (Left ) B: Chelonia mydas

(Right).

(N: Nuchal, M: Marginal, S: Supracaudal, V: Vertebral, C: Costal)

(Başoğlu and Baran, 1977).


346

as dead or alive and their scutes were counted. Both live and dead hatchlings were found in the nests at nest excavation. Also, they were encountered both in the nests and between the nests and the sea when they naturally emerged to orient toward the sea. Most of the live hatchlings found at nest excavation were in apparent good health with vigorous movements. Aft er examination, they found their way to the sea by crawling towards the coastline.

In the 2003 nesting season, the carapacial scute variation of 1086 Ch. mydas hatchlings in 81 total nests (43 nests with 169 dead and 74 nests with 917 live) and 394 C. caretta hatchlings in 25 total nests (16 nests with 74 dead and 22 nests with 320 live) from Alata beach in Mersin, Turkey were examined within carapacial scute series and in carapacial scute pattern.

Th e most frequent scute pattern observed on Alata beach was accepted as the normal scute pattern and these frequencies were similar to the ones in Canbolat (1991), Türkozan et al. (2001), Türkozan et al. (2006), and Türkozan and Yılmaz (2007). Th e normal scute pattern was 1 nuchal, 5 vertebrals, 1 pair of supracaudals, 4 pairs of costals, and 11 pairs of marginals for Ch. mydas hatchlings and 1 nuchal, 5 vertebrals, 1 pair of supracaudals, 5 pairs of costals, and 12 pairs of marginals for C. caretta hatchlings. Th e patterns that were diff erent from the normal scute patterns were accepted as abnormal scute patterns.

All data were analysed using SPSS 11.5 in order to evaluate the number, distribution, and frequency (%) of carapace scutes and the occurrence of carapacial scute variation in Ch. mydas and C. caretta hatchlings and adult individuals of Ch. mydas. Th e number of variations on the carapacial scutes of dead and live hatchlings of Ch. mydas and C. caretta were examined as to whether there was a relation between the mortality rate of hatchlings and number of variations on the carapacial scute using the Z test for comparison of 2 proportions in Minitab 13.0.

For Ch. mydas and C. caretta hatchlings, it was not possible to analyze the variation within each species statistically because the number of Ch. mydas individuals with 4, 5, or 6 variations and the number of C. caretta individuals with 3, 4, or 5 variations were low. Th erefore, the mortality rates of Ch. mydas

individuals with 0, 1, 2, or 3 variations and C. caretta

individuals with 0, 1, or 2 variations were compared

in pairs.

Results

Chelonia mydas

Th e scutes of 917 live Ch. mydas hatchlings were

counted. Th e number of vertebral scutes was 5 (90%).

Th e number of nuchal plates was 1 (95%). Th e number

of supracaudal scutes was 2 (100%). Th e numbers of

right and left costal scutes were 4-4 (88.1%), and the

numbers of right and left marginal scutes were 11-11

(95.7%). Th e scutes of 169 dead Ch. mydas hatchlings

were also counted. Th e number of vertebral scutes

was 5 (87%). Th e number of nuchal plates was 1

(94.7%). Th e number of supracaudal scutes was 2

(100%). Th e numbers of right and left costal scutes

were 4-4 (88.8%), and the numbers of right and left

marginal scutes were 11-11 (92.9%) (Table 1).

Of 169 dead Ch. mydas hatchlings, 39 hatchlings

(23.1%) had carapacial scute variation. Only 1 of them

(0.6%) had at most 5 separate variations in carapacial

scute pattern and 23 hatchlings (13.6%) had at least

1 carapacial scute variation. Of 917 live Ch. mydas

hatchlings, 201 hatchlings (21.9%) had carapacial

scute variation. Only 1 of them (0.1%) had at most

6 separate variations in carapacial scute pattern and

119 hatchlings (13%) had at least 1 carapacial scute

variation (Table 2).

Th e mortality rates of individuals with 0, 1, 2,

or 3 variations were compared in pairs. In these

comparisons, there are no signifi cant diff erences with

respect to the mortality rate of hatchlings between the

individuals with 0 and 1 variation (P = 0.803), 0 and 2

variations (P = 0.479), 0 and 3 variations (P = 0.418),

1 and 2 variations (P = 0.449), 1 and 3 variations (P =

0.518), and 2 and 3 variations (P = 0.277).

On Alata beach, the scutes of 13 adult Ch. mydas

were counted. Th e most observed numbers of scutes

were 5 for vertebral, 1 for nuchal, 2 for supracaudals,

4-4 for costal, and 11-11 for marginals (Table 3).

Considering all the observations of dead and live

hatchlings and adult individuals of Ch. mydas, the

general scute pattern was 1 nuchal (in all hatchlings

94.9%; in adult individuals 84.6%), 5 vertebrals (in


347

all hatchlings 88.5%; in adult individuals 92.3%), 2 supracaudals (in all hatchlings 100%; in adult individuals 100%), 4-4 costals (in all hatchlings 88.5%; in adult individuals 84.6%), and 11-11 marginals (in all hatchlings 94.3%; in adult individuals 100%).

No variation was observed in 69.2% of 13 adults in total. Of the 13 adults, 8 were live females found laying eggs on the beach, and 5, with sex unknown, were dead (Table 4). Th e individuals with variations had 2 variations at most (Table 4).

Table 1. Th e number, distribution, and frequency (%) of carapacial scutes of Chelonia mydas hatchlings in the 2003 nesting season at

Alata beach. L: Left R: Right N: Sample size.

Chelonia mydas Live hatchlings Dead hatchlings

L-R N = 917 % L-R N = 169 %

Nuchal1 871 95 1 160 94.7

2 46 5 2 9 5.3

Vertebrals

3 1 0.1 - - -

4 1 0.1 - - -

5 825 90 5 147 87

6 69 7.5 6 19 11.2

7 15 1.6 7 1 0.6

8 5 0.5 8 1 0.6

9 1 0.1 9 1 0.6

Supracaudals 2 917 100 2 169 100

Costals

2-2 1 0.1 - - -

3-3 1 0.1 - - -

4-4 808 88.1 4-4 150 88.8

4-5 22 2.4 4-5 6 3.6

4-6 5 0.5 4-6 1 0.6

5-4 39 4.3 5-4 7 4.1

5-5 13 1.4 5-5 5 3.0

5-6 9 1.0 - - -

5-7 2 0.2 - - -

6-4 4 0.4 - - -

6-5 4 0.4 - - -

6-6 5 0.5 - - -

6-7 1 0.1 - - -

7-7 3 0.3 - - -

Marginals

9-8 1 0.1 - - -

10-10 6 0.7 10-10 1 0.6

10-11 8 0.9 10-11 1 0.6

11-10 3 0.3 - - -

11-11 878 95.7 11-11 157 92.9

11-12 8 0.9 11-12 6 3.6

12-11 8 0.9 12-11 3 1.8

12-12 5 0.5 12-12 1 0.6


348

Caretta caretta

In 320 live C. caretta hatchlings, the number of

vertebral scutes was 5 (87.2%), the number of nuchal

plates was 1 (90.9%), the number of supracaudal scutes was 2 (100%), the numbers of right and left costal scutes were 5-5 (96.3%), and the numbers of right and left marginal scutes were 12-12 (41.3%). In 74 dead C. caretta hatchlings, the number of vertebral scutes was 5 (93.2%), the number of nuchal plates was 1 (100%), the number of supracaudal scutes was 2 (100%), the numbers of right and left costal scutes were 5-5 (95.9%), and the numbers of right and left marginal scutes were 12-12 (63.5%) (Table 5). Th ere were no data available for the adult female C. caretta.

Considering the observations of dead and live hatchlings, the general scute pattern was 1 for nuchal (95.5%), 5 for vertebral (90.2%), 2 for supracaudals (100%), 5-5 for costal (96.1%), and 12-12 for marginals (52.4%).

Of 74 dead C. caretta hatchlings, 31 hatchlings (41.9%) had carapacial scute variation. Only 1 of them (1.4%) had at most 4 separate variations in carapacial scute pattern and 16 hatchlings (21.6%) had at least 1 carapacial scute variation. Of 320 live C. caretta hatchlings, 211 hatchlings (65.9%) had carapacial

Table 2. Th e variation numbers of the carapacial scutes of Chelonia mydas hatchlings.

No variation Variation

TotalValid 0 1 2 3 4 5 6

Dea

d

Frequency 130 23 6 7 2 1 - 169

Th e percentage in the dead samples (%) 76.9 13.6 3.6 4.1 1.2 0.6 - 100

Th e percentage in 1086 samples total (%) 12 2.1 0.6 0.6 0.2 0.1 - 15.6

Liv

e

Frequency 716 119 44 26 8 3 1 917

Th e percentage in the live samples (%) 78.1 13 4.8 2.8 0.9 0.3 0.1 100

Th e percentage in 1086 samples total (%) 65.9 11 4.1 2.4 0.7 0.3 0.1 84.4

To

tal Frequency 846 142 50 33 10 4 1 1086

Th e percentage in 1086 samples total (%) 77.9 13.1 4.6 3 0.9 0.4 0.1 100

Table 3. Th e number, distribution, and frequency (%) of

carapacial scutes of adult individuals of Chelonia

mydas in the 2003 nesting season. L: Left R: Right

N: Sample size.

L-R N = 13 %

Nuchal1 11 84.6

2 2 15.4

Vertebrals5 12 92.3

6 1 7.7

Supracaudals 2 13 100

Costals

4-4 11 84.6

5-4 1 7.7

6-4 1 7.7

Marginals 11-11 13 100


349

scute variation. Only 1 of them (0.3%) had at most 5 separate variations in carapacial scute pattern and 69 hatchlings (21.6%) had at least 1 carapacial scute variation (Table 6).

Regarding the mortality of individuals with 0, 1, or 2 variations, some results suggested that the mortality rate decreased as the number of variations increased. Although there was a clear decrease in the mortality rates as the number of variations increased, there was a statistically signifi cant diff erence only between the individuals with 0 and 2 variations (P = 0.001). Th ere was no statistically signifi cant diff erence between the individuals with 0 and 1 variations (P = 0.091) or 1 and 2 variations (P = 0.139).

Discussion

Chelonia mydas

Th e examination of carapacial scute variations of 1086 specimens of Ch. mydas hatchlings in total showed that there was no statistically signifi cant diff erence (P = 0.742) between the dead (39; 23.1%) and live (201; 21.9%) hatchlings with respect to variation values.

Regarding Ch. mydas, only the individuals with 0, 1, 2, or 3 variations could be compared in pairs, but the results were not statistically signifi cant. In conclusion, no relation between the changes in variation numbers and the mortality rates were found in Ch. mydas hatchlings. It was not possible to

compare the proportion of carapacial scute variation

of the 1086 dead and live Ch. mydas hatchlings to

the 13 adult individuals since the number of adult

specimens was not suffi cient for statistical analysis.

Th e variation numbers of the carapacial scutes;

the range of variations of vertebral, costal, and

marginal plates; and the number of combinations of

costals and marginals in Ch. mydas hatchlings are

higher than those of adults at Alata beach. Özdemir

and Türkozan (2006) off er 2 explanations for the

absence of adults with deviant numbers of costal,

vertebral, nuchal, or supracaudal scutes. Th ey argue

that the hatchlings with deviant scutes die before they

mature, or the scutes change to the normal number

with growth.

Türkozan et al. (2006) concluded that there were no

big diff erences among 1164 hatchlings of Ch. mydas

in natural and relocated nests at Kazanlı beach in the

2002 nesting season with respect to the numbers of

plates in their carapaces. However, they stated that

the numbers of plate combinations changed, and

added that the number of nuchal scutes is 1 or 2 in

hatchlings from natural nests at Kazanlı beach. Th e

most common individuals were those with 1 nuchal

scute, with a rate of 89.2%, lower than that of Alata

beach. Th e total number of nuchal scutes changed

between 1 and 2 for Ch. mydas at Alata beach.

Among the hatchlings of Ch. mydas examined, the

most common number of nuchal plates was 1, found

on average in 94.9% of hatchlings.

Table 4. Th e variation numbers of the carapacial scutes of adult Chelonia mydas.

No variation Variation Total

Valid 0 1 2 3 4 5 6 Total

5 stranded dead

adults whose sex were

unknown

Frequency 4 1 - - - - 5

Percent (%) 80 20 - - - - - 100

8 live adult females

Frequency 5 2 1 - - - - 8

Percent (%) 62.5 25 12.5 - - - - 100

Total

Frequency 9 3 1 - - - - 13

Percent (%) 69.2 23.1 7.7 - - - - 100


350

At Kazanlı beach, the number of vertebrals varied

from 5 to 8 with the most common pattern being 5

vertebrals (91.9%). Th is rate was higher than that of

Alata beach. At Alata beach, the number of vertebral

scutes varied between 3 and 9, and the most observed

number of vertebral scutes was 5, found on average

in 88.5% of hatchlings. Th e range of variation at Alata beach was more than that of Kazanlı beach.

At Kazanlı beach, the number of costals varied from 4 to 7 on both sides, and 10 combinations were noted. Th e number of combinations was lower than that of Alata beach. Th e most common individuals

Table 5. Th e number, distribution, and frequency (%) of carapacial scutes of Caretta caretta hatchlings in the 2003 nesting season at Alata beach. L: Left R: Right N: Sample size.

Caretta carettaLive hatchlings Dead hatchlings

L-R N = 320 % L-R N = 74 %

Nuchal1 291 90.9 1 74 100

2 29 9.1 - - -

Vertebrals

5 279 87.2 5 69 93.2

6 32 10 6 4 5.4

7 7 2.2 7 1 1.4

8 2 0.6 - - -

Supracaudals 2 320 100 2 74 100

Costals

4-5 2 0.6 - - -

5-4 1 0.3 - - -

5-5 308 96.3 5-5 71 95.9

5-6 4 1.3 5-7 1 1.4

6-5 2 0.6 - - -

6-6 1 0.3 6-6 2 2.7

7-5 1 0.3 - - -

8-7 1 0.3 - - -

Marginals

11-10 1 0.3

11-11 120 37.5 11-11 10 13.5

11-12 20 6.3 11-12 6 8.1

12-11 28 8.8 12-11 6 8.1

12-12 132 41.3 12-12 47 63.5

12-13 9 2.8 12-13 2 2.7

13-11 1 0.3 - - -

13-12 4 1.3 13-12 1 1.4

13-13 4 1.3 13-13 2 2.7

13-14 1 0.3 - - -


351

were those with the 4-4 pattern of costals (93.8%).

Th e rate of this pattern was higher than that of Alata

beach. Th e number of costal scutes varied between 2

and 7, and 14 combinations existed at Alata beach.

Th e pattern 4-4 was observed on average in 88.5% of

hatchlings at Alata beach.

Finally, at Kazanlı beach the total number of

marginals ranged from 10 to 13 on both sides and

9 combinations were noted. Th e most common

individuals were those with the 11-11 pattern of

marginals (96.3%). Th e number of combinations at

Kazanlı beach was only 1 more than those of Alata

beach. In marginal scutes, the numbers were between

9 and 12, and there were 8 combinations at Alata

beach. Among the individuals, the most observed

ones were 11-11, found on average in 94.3% of

hatchlings. Th e number of supracaudals (2) was

constant (100%) at Kazanlı beach. Th is result is the

same as that for Alata beach.

Özdemir and Türkozan (2006) analyzed the

scutes in carapaces of Ch. mydas hatchlings from

the relocated nests at 2 diff erent nesting beaches in

Northern Cyprus (Ronas beach and Golden beach I).

Since we have no data available from the relocated

Ch. mydas nests, we are not able to compare the

variations of hatchlings in natural and relocated

nests.

In conclusion, the most common carapace plate

frequency of Ch. mydas in our study on Alata beach is

similar to the ones in the study conducted by Türkozan

et al. (2006) (the most frequent scute combination

in the carapaces of hatchlings in both natural and

relocated nests) and Özdemir and Türkozan (2006)

(the most frequent scute combination in the carapaces

of hatchlings in relocated nests). Th is frequency is 1

nuchal, 1 pair of supracaudals, 5 vertebrals, 4 pairs of

costals, and 11 pairs of marginals.

Özdemir and Türkozan (2006) stated that they

were not able to comment on whether hatchlings

in their relocated nests had a higher variation than

those of natural ones since they had no data available

from the natural Ch. mydas nests. Unlike Özdemir

and Türkozan (2006), we had data from natural nests,

not from relocated ones. Th erefore, we were not able

to compare the variations of hatchlings in natural

and relocated nests. Hence, we compared the scute

variations of the hatchlings of natural nests at Alata

in Mersin to those of relocated nests in Northern

Cyprus (Ronas beach and Golden beach I) (Table 7).

In their study of the population of Ch. mydas

hatchlings in Northern Cyprus (Golden Beach I

and Ronas Beach), Özdemir and Türkozan (2006)

stated that, out of 718 hatchlings, 290 (40.4%) had

carapacial scute variation. According to Özdemir and

Türkozan (2006), the rate of hatchlings in relocated

nests with no carapacial scute variation (59.6%)

was approximately 1.5 times higher than the rate

of hatchlings in relocated nests in which carapacial

Table 6. Th e variation numbers of the carapacial scutes of Caretta caretta hatchlings.

No variation VariationTotal

Valid 0 1 2 3 4 5

Dea

d

Frequency 43 16 13 1 1 0 74

Th e percentage in the dead samples (%) 58.1 21.6 17.6 1.4 1.4 0 100

Th e percentage in 394 samples total (%) 10.9 4.1 3.3 0.3 0.3 0 18.8

Liv

e

Frequency 109 69 103 33 5 1 320

Th e percentage in the dead samples (%) 34.1 21.6 32.2 10.3 1.6 0.3 100

Th e percentage in 394 samples total (%) 27.7 17.5 26.1 8.4 1.3 0.3 81.2

To

tal Frequency 152 85 116 34 6 1 394

Th e percentage in 394 samples total (%) 38.6 21.6 29.4 8.6 1.5 0.3 100


352

scute variation was seen (40.4%) in Northern Cyprus

(Golden Beach I and Ronas Beach). According to the

current study at Alata beach, out of 1086 hatchlings

that were examined from the natural Ch. mydas nests,

240 hatchlings (22.1%) had carapacial scute variation.

As Table 7 indicates, the rate of hatchlings with no

carapacial scute variation (77.9%) is approximately

3.5 times higher than the rate of hatchlings with

carapacial scute variation (22.1%) in natural nests

at Alata Beach. As shown in Table 7, the rate of

hatchlings with carapacial scute variation of relocated

nests of Northern Cyprus (Golden Beach I and Ronas

Beach) (40.4%) (Özdemir and Türkozan, 2006) is

almost 2 times higher than the rate of hatchlings of

natural ones (22.1%) at Alata beach. Futhermore,

in the natural nests at Alata beach, a total of 1086

Ch. mydas hatchlings have at most 6 variations on

their carapacial scutes, and in the relocated nests in

Northern Cyprus, a total of 718 Ch. mydas hatchlings

have at most 6 variations on their carapacial scutes

(Özdemir and Türkozan, 2006). In short, the results

are the same in the 2 studies.

Caretta caretta

Th e examination of carapacial scute variation

of 394 total specimens (74 dead and 320 live) of C.

caretta hatchlings showed that the proportion of 211

live hatchlings with scute variation (65.9%) was higher

than the proportion of 31 dead hatchlings (41.9%) (P

< 0.001). Regarding C. caretta, some results suggest

that the mortality rate decreased as the number of

variations increased in individuals with 0, 1, or 2

variations. Although there was a clear decrease in the

mortality rate as the number of variations increased,

there was a statistically signifi cant diff erence only

between the individuals with 0 and 2 variations (P

= 0.001). However, it was not possible to conclude

that the mortality rate decreased as the number of

variations increased because the diff erence between

the individuals with other variation numbers was

not statistically signifi cant. If the mortality rates

decreased as the number of variation increased,

the percentage of adults with deviant scutes would

be very high. However, in adults the proportion of

variation is less than that of hatchlings (Gadow,

1899). As a result, there was no relation between the

changes of variation numbers and the mortality rate.

In his study on the population of C. caretta

at Dalyan beach, Canbolat (1991) examined the

carapacial scute variation of 71 adults and 497

hatchlings. Türkozan et al. (2001) analyzed the

scutes of the carapaces of adult female and hatchling

C. caretta in 5 nesting beaches in Turkey (Dalyan,

Fethiye, Belek, and Kızılot) and Northern Cyprus

(Karpaz). Th ey studied all the hatchlings from 5

Table 7. Comparison between the carapacial scute variation of Chelonia mydas hatchlings in natural nests of Alata Beach and Chelonia mydas hatchlings in relocated nests of Northern Cyprus.

Chelonia mydas

Natural nests of

Alata Beach (Th is study)

Relocated nests of Northern Cyprus

(Ronas beach and Golden beach I) *

Variation

Frequency 240 290

Percent (%) 22.1 40.4

No variation

Frequency 846 428

Percent (%) 77.9 59.6

Total Frequency 1086 718

* According to Özdemir and Türkozan (2006).


353

beaches and determined a general scute pattern. Türkozan et al. (2006) determined that the numbers of scutes of 1052 hatchlings of C. caretta in natural and relocated nests at Fethiye beach in the 2003 nesting season did not show big diff erences; however, they stated that scute combinations varied. In their study at Dalyan beach in Turkey in the 2004 season (June to early August), Türkozan and Yılmaz (2007) examined diff erences in carapacial scute patterns, and sizes and weights of 734 hatchlings from 34 in situ nests and 1188 hatchlings from 49 hatchery-relocated nests. Th ey found that the vertebral, costal, and marginal series were the most variable and the supracaudal scutes were extremely stable.

In this study, we compared the scute variation patterns of hatchlings in natural nests of Alata beach to those of hatchlings in natural nests of the above mentioned beaches studied by other researchers. Th e total number of nuchal scutes varied between 1 and 2 for C. caretta at Alata beach. Th e most observed number of nuchals among hatchlings was 1, found on average in 95.5% of hatchlings. In Canbolat’s (1991) study, the numbers of nuchal scutes were observed as 1, 2, or 3 and the most observed number was 1 (95.6%). In the studies by Türkozan et al. (2001), Türkozan et al. (2006), and Türkozan and Yılmaz (2007), the total number of nuchal scutes varied between 1 and 2 and the most observed structure was 1. Th e rates were 97.5%, 93.2%, and 95.2%, respectively.

Th e numbers of vertebrals varied between 5 and 8 at Alata beach. Th e most observed number of vertebrals was 5, found on average in 90.2% of hatchlings. Th ese numbers were between 5 and 8 in Canbolat’s (1991) study, and the most observed numbers of vertebrals were at the rate of 94.6%. In Türkozan et al. (2001), the numbers of vertebrals changed between 4 and 9, and the most observed number of vertebral scutes was 5 (89.9%) Th e numbers of vertebrals varied between 4 and 8 and the most observed number of vertebral scutes was 5 (81.59%) (Türkozan et al., 2006). In Türkozan and Yılmaz (2007), the number of vertebral scutes varied between 5 and 8. Th e most observed number was 5 with a rate of 92%.

At Alata beach, the numbers of costals varied between 4 and 8, and there were 8 combinations. Among the individuals, 5-5 was the most common pattern, found on average in 96.1% of hatchlings.

In Canbolat (1991), the numbers of costals were between 3 and 7, and there were 10 combinations. Th e most common pattern was 5-5, and the average rate was 95.2%.

In Türkozan et al. (2001), the numbers of costal scutes varied between 4 and 8 on either side, and there were 14 combinations. Among the individuals 5-5 was most frequently observed (93.3%). In Türkozan et al. (2006), the numbers of costal scutes varied between 4 and 8 and there were 18 combinations. A 5-5 pattern was the most common (85.4%). In Türkozan and Yılmaz (2007), the numbers of costal scutes varied between 4 and 7, and there were 11 combinations. A 5-5 pattern was the most commonly seen at a rate of 92.1%.

At Alata beach, the marginal scutes varied between 10 and 14 and there were 10 combinations. Th e most common individuals were those with the 12-12 pattern, which was found on average in 52.4% of hatchlings. Th e marginal scutes varied between 10 and 13 and there were 10 combinations in Canbolat (1991). A 12-12 pattern was most frequently observed with a rate of 42.5%. In Türkozan et al. (2001), there were variations between 9 and 13 on each side in the total number of marginals. Th ere were 14 combinations, and among the individuals, 12-12 was most oft en seen (63.3%). In Türkozan et al. (2006), the numbers of marginal scutes were between 11 and 13, and there were 6 combinations. A 12-12 pattern was most oft en seen (55.7%). Th e numbers of marginal scutes varied between 10 and 14 and there were 11 combinations in Türkozan and Yılmaz (2007). A 12-12 pattern was most commonly seen (62.5%).

In all specimens, supracaudals were determined to be 2 at Alata beach. Both at Alata beach and in other studies (Canbolat, 1991; Türkozan et al., 2001; Türkozan et al., 2006; Türkozan and Yılmaz, 2007), the numbers of supracaudals were also exclusively 2.

In conclusion, the most commonly seen carapace scute frequency of C. caretta in our study on Alata beach is similar to the ones in Canbolat (1991), Türkozan et al. (2001), Türkozan et al. (2006) (the most frequent scute combination in the carapaces of hatchlings in both natural and relocated nests), and Türkozan and Yılmaz (2007) (the most frequent scute combination in the carapaces of hatchlings in


354

both natural and relocated nests). Th is frequency is 1 nuchal, 1 pair of supracaudals, 5 vertebrals, 5 pairs of costals, and 12 pairs of marginals.

Since our data were limited to only the natural nests, not from relocated ones, we were not able to compare the variations of hatchlings in natural and relocated nests. When the scute variations of the hatchlings of natural nests of Alata beach and those of natural and relocated nests of Dalyan beach (Türkozan and Yılmaz, 2007) were compared, the rate of carapacial scute variation of natural nests of Alata beach (61.2%) was higher than the rate of natural (44.4%) and relocated (46.0%) nests of Dalyan beach (Table 8).

Scute variation is common in hatchlings. Scute deviation is signifi cantly higher in Ch. mydas hatchlings from a hatchery than in the hatchlings from natural nests (Suganuma et al., 1994). Th is is also true for the C. caretta nests in Turkey (Türkozan and Yılmaz, 2007). Accordingly, the variation of hatchlings from potential relocated nests is likely to be higher than that of hatchlings from natural nests on Alata beach.

Some scientists have tried to explain the factors which cause variation of scutes in hatchlings. Mast and Carr (1989) state that handling of the eggs aft er a turtle’s ovoposition has a signifi cant eff ect on the variation of the structures in the hatchling’s carapace. Hill (1971) reports that in Olive Ridley (Lepidochelys olivacea), handling eggs at certain stages of development has increased scute variation.

Transplantation, translocation and artifi cial

incubation of sea turtle eggs possibly have eff ects

on the viability of hatchlings (Mast and Carr, 1989).

Th erefore, the in situ protection must be preferred

not only because of low percentages of scute

deviation but also because of high percentages of

nest success obtained (Carretero-Montes and Trejo-

Robles, 2000). Also, with the in situ protection the

natural sex ratio of hatchlings is maintained (Boulon,

1999). According to Ewert (1979), the structure of

the carapace in specimens has a certain period for

change. It is stated that in the middle third of the

incubation period, gonadal diff erentiation in turtles

occurs (Yntema and Mrosovsky, 1982).

On the other hand, Başkale and Kaska (2003)

state that relocating nests that are at risk of predation

and fl ood can be useful in terms of increasing the

percentage of successful hatchling emergence. It is

crucial to obey the rules for relocating nests in order

to ensure continuity of marine turtle generations.

Whether the method applied is trustworthy or not

would be clear when the percentages of nest success

and percentages of scute deviations in relocated nests

are compared to those in natural nests. Variation

of numbers of scutes in hatchlings may depend on

diff erent factors. Understanding several diff erent

environmental factors that might infl uence the

variations seen in carapaces in natural and relocated

nests may contribute to scientists making choices to

move clutches to protect marine turtles (Özdemir

and Türkozan, 2006).

Table 8. Comparison between the carapacial scute variation of Caretta caretta hatchlings in natural nests of Alata Beach and Caretta

caretta hatchlings in relocated nests of Dalyan Beach.

Caretta caretta

Natural nests of

Alata Beach

(Th is study)

Natural and relocated nests of Dalyan Beach **

Natural Nests Relocated Nests

VariationFrequency 241 326 546

Percent (%) 61.2 44.4 46.0

No variationFrequency 153 408 642

Percent (%) 38.8 55.6 54.0

Total Frequency 394 734 1188

** According to Türkozan and Yılmaz (2007).


355

Since the data compared were obtained from

diff erent beaches (Alata beach in Mersin, Golden

beach I and Ronas beach in Northern Cyprus, and

Dalyan beach in Muğla), the diff erent properties

of the beaches must be taken into consideration. If

the nests of C. caretta and Ch. mydas in Alata beach

need relocating in subsequent years, a comparison

of the variations of hatchlings to be examined in the

natural and relocated nests will reveal to what extent

the relocation of nests will change the variations. We

also think that in situ protection must be preferred

unless the relocation is needed for nest success and

the evolution and the survival of the hatchlings.

While the carapacial scute variation of hatchlings is

determined from both the dead and live hatchlings

whose sex are unknown, the carapacial scute

variation of adults is determined mostly from the

mature females emerging from the sea for nesting.

We think that the carapacial scute variation should

be determined from the dead hatchlings whose sex

ratio is estimated by histological analysis of gonads

(Yntema and Mrosovsky, 1980). Also, in the studies

determining carapacial scute variation of adults, the

number of male individuals should be increased.

Th is will ensure that the comments on the carapacial

scute variation of marine turtle populations will be

more reliable.

Acknowledgement

We would like to thank the Mersin University

Research Fund (Project No: BAB- FEF- BB

(SEG) 2002) , the Republic of Turkey Ministry of

Environment and Forest, Directorate of Environment

and Forest of Mersin City, and the Alata Horticultural

Research Institute for supporting this study. We

would like to thank Assoc. Prof. Dr. Bahar Taşdelen

and Res. Ast. Mehmet Ali Sungur for comments on

the statistical analysis.

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